The present invention generally relates to power protection systems for electrical devices. More specifically, the present invention relates to one or more embodiments of a novel fast-acting power protection system that incorporates a discrete MOSFET as a power switch unit and a current-limiting block control unit in hybrid substrates. The present invention also relates to a method for protecting an electrical device against voltage/current surges or reverse polarity input connections.
Many electrical devices today operate in environments susceptible to unwanted and dangerous power surges or accidental reverse polarity input connections. If power surges (i.e. involving a voltage surge, a current surge, or both) are sufficiently high or prolonged beyond a negligible duration, electrical devices subject to power surges can sustain operation failure or permanent damages. Therefore, protection against power surges have been commonly addressed by conventional fuses with thermal or magnetic elements, which are designed to cut off incoming electrical power.
One example of a conventional fuse is a polymeric positive temperature coefficient (PPTC) device, which exhibits a high inherent resistance than a metallic fuse or a circuit breaker. Therefore, while PPTC's are used in applications where slow power protection responses are acceptable, they are often undesirable in electronic circuits which require fast power protection responses and high energy efficiencies. Relays have been also incorporated in some electrical systems to block current or voltage surges bidirectionally. Furthermore, a transient blocking unit (TBU) is also used to protect sensitive electrical circuits which require higher performance parameters than what can be satisfied with conventional fuses or relays.
Earlier designs for transient blocking units (TBU's) were unable to perform a reset in case of a short-lived transient power surge event, thereby inconveniencing device users. Furthermore, most TBU designs are generally incapable of protecting electrical circuits if a power surge event is sufficiently prolonged (i.e. non-transient). Newer TBU designs, such as a design disclosed by U.S. Pat. No. 7,576,962, incorporates a reset feature as an effort to provide more control for surge event protection.
In most of the conventional power protection system designs, including conventional fuses, relays, and TBU's, it is difficult to achieve a fast, stiff, and durable surge protection responses. Because conventional power protection system designs tend to involve at least some slow-response components such as polymer-based devices, a reduction or a shut-down of over-current and/or over-voltage event is often slower than desirable. Furthermore, conventional power protections also typically suffer from fatigue and incremental degradation in protection performances over time.
Accordingly, a novel power protection system and a related method, which provide a rapid and reliable voltage, current, and reverse polarity protection, may be advantageous. Furthermore, a novel power protection system and a related method, which enable a lower footprint and a lower energy consumption by reducing or eliminating discrete package polymers in a protection circuit, may also be advantageous.
Moreover, a novel power protection system and a related method, which utilize hybrid substrates to combine or separate at least one of a current-limiting control IC component, a MOSFET-based power switch component, and a voltage clamp component within a single semiconductor package, may also be advantageous for achieving design and manufacturing scalability, cost efficiency, and reliability.